Dependency Object

A small object can hold a dependency value and expose the operation that uses it.

dependency_object.cpp

#include <iostream>

struct Multiplier {
    int factor;

    int apply(int value) const {
        return value * factor;
    }
};

int main() {
    int factor = ;

    Multiplier multiplier{factor};
    int input = 7;
    int output = multiplier.apply(input);

    std::cout << "factor=" << factor << std::endl;
    std::cout << "input=" << input << std::endl;
    std::cout << "output=" << output << std::endl;
    return 0;
}

#include <iostream>

struct Multiplier {
    int factor;

    int apply(int value) const {
        return value * factor;
    }
};

int main() {
    int factor = ;

    Multiplier multiplier{factor};
    int input = 7;
    int output = multiplier.apply(input);

    std::cout << "factor=" << factor << std::endl;
    std::cout << "input=" << input << std::endl;
    std::cout << "output=" << output << std::endl;
    return 0;
}

#include <iostream>

struct Multiplier {
    int factor;

    int apply(int value) const {
        return value * factor;
    }
};

int main() {
    int factor = ;

    Multiplier multiplier{factor};
    int input = 7;
    int output = multiplier.apply(input);

    std::cout << "factor=" << factor << std::endl;
    std::cout << "input=" << input << std::endl;
    std::cout << "output=" << output << std::endl;
    return 0;
}

dependency Instead of hiding a value in a global variable, store it in an object that receives it directly.

method A const method can use the stored value without changing the object.